(4aR trans) 3,4,4a,5,6,10b hexahydro 4-propyl-2H-naphth[1,2-b]-1,4-oxazin-9-ol (Compound I) represented by the formula ##STR1## is a highly potent dopamine agonist and is useful in the treatment of Parkinson's disease. The compound was first called (+)-4-propyl-9-hydroxynaphthoxazine and is often referred to by that name or by (+)-PHNO in the pharmacological and clinical literature. It is also known in the literature as trans-1a,2,3,-4a,5,6-hexahydro-9-hydroxy-4-propyl-4H-naphth[1,2]-1,4-oxazi ne. For convenience, it will hereinafter be referred to generally by (+)-PHNO. The compound is a white powder with a melting point of 162.degree.-164.degree. C. as a free base and 300.degree. C. as the hydrochloride salt. The preparation of the drug is described in U.S. Pat. No. 4,420,480. The pharmacological properties may be found described in an article by G. E. gartin et al., J. Pharm. & Exptl Ther. 230 569(1984).
Treatment entails long term therapy. It has been found that erratic durations of action develop and managing fluctuations is the most troublesome issue in oral treatment of Parkinson's disease either with levodopa or dopamine agonists. One of the ways which may be employed to overcome the problem of fluctuation is to employ intravenous infusion. However, this is a burdensome method.
Oral administration of (+)-PHNO at desirable doses may produce vomiting and other side reactions. Another method of application of the drug attempted was application to the skin using a hydroalcoholic solution. However, the solution dried to a viscous residue and provided uncontrolled delivery of the drug to the skin. Safe handling of this solution by the patient was not possible.
Thus, it is desirable to provide a safe and effective means for administering (+)-PHNO over an extended period at a suitably and reliably controlled rate.